1. Field of the Invention:
The invention relates to a process for cleaning an exhaust gas containing a pollutant, such as formaldehyde, carbon monoxide, nitrogen oxide, hydrocarbons and hydrogen cyanide, from a combustion apparatus, such as an internal combustion engine or furnace, which is operated with liquid or gaseous fuel.
2. Description of the Prior Art:
Selective catalyst processes, so-called Selective Catalytic Reduction (SCR) processes, are known, in which ammonia is used as a reduction agent, and in which a catalyst is used to reduce an No.sub.x (oxides of nitrogen). These processes are based on so-called "clean" exhaust gases. Such "clean" exhaust gases are formed in chemical plants, for example, nitric acid plants or adipic acid plants. But, if so-called smoke gases containing pollutants are present, SCR processes cannot be used without modification. Before reduction, the smoke gases must be cleaned by washing or by another method, for example, by filtering. An example of an SCR process is described in U.S. Pat. No. 4,521,388.
Some examples of catalytic technology are found in U.S. Pat. No. 4,259,312, entitled "Process And Apparatus For Catalytically Reacting A Reducing Gas and Water Vapor"; U.S. Pat. No. 4,235,604, entitled "Method For Processing Coke Oven Gas"; and U.S. Pat. No. 4,049,777, entitled "Method of Waste Gas Treatment", all of which are assigned to at least one of the same assignees of the instant application.
Further examples of catalytic technology are found in U.S. Pat. No. 4,448,895, entitled "Process For Preparation of Catalyst For Cleaning Exhaust Gases and Catalyst Prepared For The Process"; U.S. Pat. No. 4,503,162, entitled "Catalyst Systems For The Conversion Of Gases"; and U.S. Pat. No. 4,044,102, entitled "Method For Treating Exhaust Gases". All of the abovecited patents are incorporated herein by reference.